Derivatives of 6-aminopenicillanic acid

ABSTRACT

Novel 6-methoxy and 6-thioalkyl-6-acylamidopenicillanic acids and their non-toxic pharmaceutically-acceptable salts, esters and amides which are useful as antibiotics. The products are prepared by treating an ester of 6-substituted-6-aminopenicillanic acid with an acylating agent followed by removal of the ester group. Also disclosed are novel intermediates.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of copending U.S. Ser. No.149,349, filed June 2, 1971, now abandoned.

BACKGROUND OF THE INVENTION

This invention relates to new antibiotics, new intermediate productsuseful in the preparation of these antibiotics, and processes for thepreparation of these compounds. More particularly, it is concerned withnew 6-aminopenicillanic acid derivatives having a methoxy or thioalkylsubstituent at position 6, and with new intermediates and processes fortheir production.

The discovery of penicillin, which was found to be such an important andeffective antibiotic, stimulated great interest in this field.Subsequently, various other antibiotics such as streptomycin, thetetracyclines, novobiocin, and the like were found which greatlyincreased the doctors' armamentarium for treating infections due to avariety of pathogens. Unfortunately, the use of these antibiotics gaverise to strains of pathogens resistant to these known antibiotics. Inaddition, the known antibiotics suffer from the disadvantage that theyare only effective against certain types of microorganisms and are noteffective against a broad range of pathogens. Accordingly, the searchfor other antibiotics has continued.

It is an object of this invention to provide new penicillins havingantibiotic activity. A further object is to provide processes for thepreparation of these new antibiotics. Another object is to provide newintermediates useful in preparing these new penicillins. Other objectswill be apparent from the detailed description of this inventionhereinafter provided.

The new penicillins of the present invention are compounds wherein thepenam nucleus, namely a thioazolidine ring with a fused β-lactam,contains a methoxy or thiomethyl substituent at the 6-position. Thus,these new penicillins which can be represented by the structuralformula: ##STR1## wherein R' represents an acyl group and R₁ is methoxyor thioloweralkyl or 1-6 carbon atoms; n is 0 or 1; and derivativesthereof, such as esters, amides, and salts, are valuable new antibioticsubstances. Compounds wherein R₁ is thiolower alkyl are also valuable asintermediates to make the 6-methoxy compounds. Compounds where n=1 arealso valuable intermediates to make novel cephalosporins.

The acyl radical represented by R' can be a substituted or unsubstitutedaliphatic acyl, aromatic acyl, heterocyclic acyl, araliphatic acyl orheterocyclylaliphatic acyl radical derived from a carboxylic acid or acarbothioic acid such as the acyl radicals of the known cephalosporinsand penicillins. These acyl radicals can be represented by the generalformula: ##STR2## where R₂ is a radical of the group defined below, mand n represent 0-4 and R₃ represents R" or ZR", which are definedbelow.

One group of acyl radicals can be represented by the acyl group generalformula: ##STR3## wherein R" represents a substituted or unsubstitutedstraight or branched chain alkyl, alkenyl or alkynyl; aryl; aralkyl;cycloalkyl; heteroaryl or heteroaralkyl. dibromomethyl,1-(3-methylimidazolyl)methyl, 2- or 3-(5-carboxymethylthienyl)methyl, 2-or 3-(5-carbamoylthienyl)-methyl, 2- or 3-(5-methylthienyl)methyl, 2- or3-(5-methoxythienyl)methyl, 2- or 3-(5-chlorothienyl)methyl, 2- or3-(5-sulfothienyl)methyl, 2- or 3-(5-carboxythienyl)methyl,3-(1,2,5-thiadiazolyl)methyl, 3-(4-methoxy-1,2,5-thiadiazolyl)methyl,2-furylmethyl, 2-(5-nitrofuryl)methyl, 3-furylmethyl, 2-thienylmethyl,3-thienylmethyl, and 1-tetrazolylmethyl.

The acyl group can also be a radical of the formula: ##STR4## wherein nis an integer of 0-4, Z is oxygen or sulfur, and R" is defined as above.Representative members of the substituent

    --(CH.sub.2).sub.n ZR"

that might be mentioned are allylthiomethyl, phenylthiomethyl,butylmercaptomethyl, α-chlorocrotylmercaptomethyl, phenoxymethyl,α-phenoxyethyl, α-phenoxybutyl, phenoxybenzyl, diphenoxymethyl,dimethylmethoxymethyl, dimethylbutoxymethyl, dimethylphenoxymethyl,4-guanidinophenoxymethyl, 4-pyridylthiomethyl,p-(carboxymethyl)phenoxymethyl, p-(carboxymethyl)phenylthiomethyl,2-thiazolylthiomethyl, p-(sulfo)phenoxymethyl,p-(sulfo)phenylthiomethyl, p-(carboxy)phenoxymethyl,p-(carboxy)phenylthiomethyl, p-(carboxymethyl)phenoxymethyl,p-(carboxymethyl)phenylthiomethyl, 2-pyrimidinylthiomethyl,phenethylthiomethyl, 1-(5,6,7,8-tetrahydronaphthyl)oxomethyl,6,8-bis(methylthio)octanoyl.

Alternatively, the acyl group can be a radical of the formula: ##STR5##These groups can be unsubstituted or can be substituted by radicals suchas alkyl, alkoxy, halo, cyano, carboxy, sulfoamino, carbamoyl, sulfonyl,azido, amino, substituted amino, haloalkyl, carboxyalkyl,carbamoylalkyl, N-substituted carbamoylalkyl, guanidino, N-substitutedguanidino, guanidinoalkyl, and the like. Representative examples of suchacyl groups that might be mentioned are those wherein R" is benzyl,p-hydroxybenzyl, 4-amino-4-carboxybutyl, methyl, cyanomethyl,2-pentenyl, n-amyl, n-heptyl, ethyl, 3- or 4-nitrobenzyl, phenethyl,β,β-diphenylethyl, methyldiphenylmethyl, triphenylmethyl,2-methoxyphenyl, 2,6-dimethoxyphenyl, 2,4,6-trimethoxyphenyl,3,5-dimethyl-4-isoxazolyl, 3-butyl-5-methyl-4-isoxazolyl,5-methyl-3-phenyl-4-isoxazolyl,3-(2-chlorophenyl)-5-methyl-4-isoxazolyl,3-(2,6-dichlorophenyl)-5-methyl-4-isoxazolyl, D-4-amino-4-carboxybutyl,D-4-N-benzoylamino-4-carboxy-n-butyl, p-aminobenzyl, o-aminobenzyl,m-aminobenzyl, (3-pyridyl)methyl, 2-ethoxy-1-naphthyl,3-carboxy-2-quinoxalinyl,3-(2,6-dichlorophenyl)-5-(2-furyl)-4-isoxazolyl, 3-phenyl-4-isoxazolyl,5-methyl-3-(4-guanidinophenyl)-4-isoxazolyl, 4-guanidinomethylphenyl,4-guanidinomethylbenzyl, 4-guanidinobenzyl, 4-guanidinophenyl,2,6-dimethoxy-4-guanidinophenyl, o-sulfobenzyl, p-carboxymethylbenzyl,p-carbamoylmethylbenzyl, m-fluorobenzyl, m-bromobenzyl, p-chlorobenzyl,p-methoxybenzyl, 1-naphthylmethyl, 3-isothiazolylmethyl,4-isothiazolylmethyl, 5-isothiazolylmethyl, 4-pyridylmethyl,5-isoxazolylmethyl, 4-methoxy-5-isoxazolylmethyl,4-methyl-5-isoxazolylmethyl, 1-imidazolylmethyl, 2-benzofuranylmethyl,2-indolylmethyl, 2-phenylvinyl, 2-phenylethynyl,2-(5-nitrofuranyl)vinyl, phenyl, o-methoxyphenyl, o-chlorophenyl,o-phenylphenyl, p-aminomethylbenzyl, 1-(5-cyanotriazolyl)methyl,difluoromethyl, dichloromethyl, wherein R" is defined as above and R'"is amino, hydroxy, azido, carbamoyl, guanidino, acyloxy, halo,sulfamino, tetrazolyl, sulfo, carboxy or carbalkoxy. Representativemembers of the substituent that might be mentioned are α-aminobenzyl,α-amino-2-thienylmethyl, α-methylaminobenzyl,α-amino-γ-methylmercaptopropyl, α-amino-3 or 4-chlorobenzyl, α-amino-3or 4-hydroxybenzyl, α-amino-2,4-dichlorobenzyl,α-amino-3,4-dichlorobenzyl, D(-)-α-hydroxybenzyl, α-carboxybenzyl,α-amino-3-thienylmethyl, D(-)-α-amino-3-chloro-4-hydroxybenzyl,D(-)-α-amino-3-thienylmethyl, 1-aminocyclohexyl,α-(5-tetrazolyl)-benzyl, α-sulfaminobenzyl, α-sulfamino-3-thienylmethyl,α-(N-methylsulfamino)benzyl, D(-)-α-guanidino-2-thienylmethyl,D(-)-α-guanidinobenzyl, α-guanylureidobenzyl, α-hydroxybenzyl,α-azidobenzyl, α-fluorobenzyl, 4-(5-methoxy-1,3-oxadiazole)-aminomethyl,4-(5-methoxy-1,3-oxadiazole)-hydroxymethyl,4-(5-methoxy-1,3-oxadiazole)-carboxymethyl,4-(5-methoxy-1,3-sulfadiazole)-aminomethyl,4-(5-methoxy-1,3-sulfadiazole)-hydroxymethyl,4-(5-methoxy-1,3-sulfadiazole)-carboxymethyl,2-(5-chlorothienyl)-aminomethyl, 2-(5-chlorothienyl)-hydroxymethyl,2-(5-chlorothienyl)-carboxymethyl, 3-(1,2-thiazole)-aminomethyl,3-(1,2-thiazole)-hydroxymethyl, 3-(1,2-thiazole)-carboxymethyl,2-(1,4-thiazolyl)-aminomethyl, 2-(1,4-thiazolyl)-hydroxymethyl,2-(1,4-thiazolyl)-carboxymethyl, 2-benzothienylaminomethyl,2-benzothienylhydroxymethyl, 2-benzothienylcarboxymethyl,2-azidooctyl-3-phenyl-3-azidomethyl, α-phosphonobenzyl andα-sulfobenzyl.

Alternatively, the group ##STR6## can be a sulfonamido group such asphenylsulfonamido, ethylsulfonamido, benzylsulfonamido,2,5-dimethylsulfonamido, 4-chlorosulfonamido, 4-chlorophenylsulfonamido,4-methoxysulfonamido, and the like.

The acyl substituents of the general formula: ##STR7## wherein R₁₀ andR₁₁ are as defined below represent a preferred group of substituentsbecause of their generally enhanced antibiotic activity. R₁₀ ishydrogen, amino, guanidino, hydroxy, carboxy, tetrazolyl, sulfo orsulfamino. R₁₁ is phenyl, substituted phenyl, a monocyclic 5- or6-membered heterocyclic ring containing one to four hetero atomsselected from oxygen, sulfur, nitrogen or phenylthio.

Examples of these preferred acyl substituents that might be mentionedare phenylacetyl, 4-carboxylmethylphenylacetyl, 2-carboxyphenylacetyl,2-methyl-2-phenoxyacetyl, 3-furylacetyl, 2-thienylacetyl, phenoxyacetyl,3-thienylacetyl, 3-isothiazolylacetyl, 4-isothiazolylacetyl,phenylthioacetyl, 4-pyridylthioacetyl, tetrazolylacetyl,α-fluorophenylacetyl, D-phenylglycyl, 3-hydroxy-D-phenylglycyl,2-thienylglycyl, 3-thienylglycyl, phenylmalonyl, 3-thienylmalonyl,α-sulfaminophenylacetyl, α-hydroxyphenylacetyl, α-tetrazolylphenylacetyland α-sulfophenylacetyl.

The new penicillins of this invention can be used as antibiotics in theform of derivatives such as metal salts, for example, sodium potassiumor ammonium salts, amine salts, for example, procaine, orN,N'-dibenzylethylenediamine salts, or amides and substituted amides, asis well known in this art.

Alternatively, labile esters which are metabolized readily such asgroups of the formula --CH₂ OCO(CH₂)_(n) --A where n is an integer from0 to 5 and A is an unsubstituted or substituted aliphatic, alicyclic,aromatic or heterocyclic radical represent preferred species of esterderivatives suitable for use in antibiotic therapy. Other esters of thenew penicillins such as lower alkyl, aralkyl, aryl, silyl, halo loweralkyl, or stannyl esters are suitable for use as intermediates inpreparing the free acid and salts thereof in accordance with methodsknown in this art.

In accordance with the present invention, it is now found that the newpenicillins of this invention can be prepared by processes which can bedepicted as follows: ##STR8##

In the foregoing flowsheet the starting compound is a derivative of6-diazopenicillanic acid wherein the carboxy group is preferablyblocked, for example, by forming a suitable ester. These6-diazopenicillanic acid esters are readily prepared by esterifying6-aminopenicillanic acid and reacting the ester with nitrite. Thus, the6-aminopenicillanic acid can be esterified in accordance with methodswell known in this art to obtain, for example, the esters wherein R₈represents an alkyl group such as methyl, t-butyl, and the like, ahaloalkyl group such as trichloroethyl, an alkenyl group such as allyl,an alkynyl group such as propargyl, an aralkyl group such as benzyl,p-methoxybenzyl, o-nitrobenzyl, an organometallic group, for example, asilyl group such as trimethylsilyl, or a stannyl group such astributyltin or phenacyl. The 6-diazopenicillanic acid ester (II) isconverted by reaction with a compound of the formula: XY, to formintermediate product (III) wherein X represents halogen and Y is anitrogenous substituent or R₁. Similarly a mixture of compounds one ofwhich is the source of a positive halogen is an N-haloamide such asN-bromosuccinimide, N-bromophthalimide or N-bromoacetamide or halo andthe other of which is a source of Y. Intermediate compound (III) is thenconverted to compound (IV) in which Z' represents a nitrogenous groupwhich is readily convertible to amino or acylamino. Compound (IV) isthen converted to the desired penicillin ester which can be reacted toobtain the corresponding penicillin acid or a salt thereof. Theprocesses for carrying out the various steps of the foregoing flowsheetwill be more readily understood from the detailed descriptions ofmethods which can be used to carry out these processes.

Thus, in accordance with one specific embodiment of this invention, thenew penicillins are obtained by the following processes: ##STR9##

In the one variation of the above process the diazopenicillanic acidester (II) is reacted with a halo azide from the group consisting ofbromine, chlorine, or iodine azide, preferably in the presence of atertiary amine azide, to produce the intermediate6-halo-6-azidopenicillanic acid ester (V) which on reaction with asuitable nucleophilic reagent such as methanol or loweralkyl sulfenylbromide, is converted to the desired 6-R₁ -6-azidopenicillanic acidester (VI). Alternatively, II is treated with an alcohol or thiolhyophalite to give Va which is treated with azide anion to give VI. Thisintermediate product is reduced and acylated in one step to form thesubstituted penicillanate ester (IX) which can then be cleaved to removethe blocking group and obtain the penicillanic acid or a salt thereof(X). Alternatively, as shown in the flowsheet, the 6-R₁-6-azidopenicillanic acid ester (VI) is reduced to the 6-R₁-6-aminopenicillanic acid ester (VII) which can be acylated to producethe 6-R₁ -6-acylaminopenicillanic acid ester (IX), or the ester group ofcompound (VII) can be cleaved to obtain the free acid (VIII) which canbe acylated to form the desired substituted penicillanic acid or a saltthereof. The step of cleaving the blocking group is readily effected inaccordance with methods known in this art. For example, an aralkyl groupsuch as the benzyl ester is removed by reduction, a silyl ester can beremoved by hydrolysis to form the free acid or a salt thereof. In thisprocess other esters which are readily cleaved to form the free acid astrichloroethyl, p-methoxybenzyl, o-nitrobenzyl, phenacyl and t-butyl andthe like can be used.

The step of producing the halo azide intermediate is carried out byreacting the diazo compound with a halo azide at a temperature betweenabout 0 ° and -50° C. for sufficient time to complete the formation ofthe desired compound. The reaction is preferably carried out in asuitable organic solvent medium which is inert to the reactants. Varioussolvents which do not contain an active hydrogen such as methylenechloride, chloroform, benzene, toluene, ether and the like, or mixturesthereof provide suitable mediums for carrying out the reaction.Generally, it is preferred to effect the reaction in the presence of asecond azide such as lithium azide or a tertiary ammonium azide, forexample triethylammonium azide, since under these conditions theformation of the undesired 6-dibromo compound is avoided. The halo azideis used in an amount in slight excess of stoichemetric requirements. Theamount of second azide is not critical and it is generally desirable touse an excess in order to obtain maximum yields of the desired haloazido compound under optimum conditions. After completion of theformation of the halo azide the product is recovered and can be purifiedfurther, for example by chromatography, in accordance with processeswell known in this art.

The next step of the process, comprising the replacement of the halosubstituent, is effected by reacting the halo azide with a substancecapable of furnishing the methoxy or thiomethyl group to replace thehalo. This reaction can be carried out in the presence of a suitablenonreactant solvent such as methylene chloride, chloroform, benzene,toluene, ether, petroleum ether and the like, or preferably using thenucleophile itself, e.g., methanol, as solvent. The reaction ispreferably carried out in the presence of a suitable acid scavenger suchas an alkali or preferably a tertiary amine such an pyridine or a silversalt such Ag₂ O, AgBF₄, AgOSO₂ CF₃.

In the next step of the above-described process the 6-azido-6-R₁compound is then reduced to afford the corresponding 6-amino-6R₁compound. Various methods of carrying out this reduction can beemployed, but it is generally preferred to carry out the reduction ofthe azido to the amino group by catalytic hydrogenation employing anobel metal catalyst such as platinum, palladium or oxides thereof.These processes are carried out in accordance with procedures well knownin this art. Alternatively, the reduction can be effected in thepresence of a suitable acylating agent to produce the desired6-acylamido-6R₁ compound. The 6-amino compound can be reacted withsuitable acylating agents using procedures well known in this art toobtain the desired 6-acylamido compounds.

The sulfoxide form of the penicillin (n=1) is prepared by oxidizing apenicillin using oxidizing agents known in the art, or by oxidizing the6-amino-6-R₁ -penicillin intermediates and then acylating.

EXAMPLE 1 6β-Acetamido-6-methoxypenicillanic Acid and Sodium Salt StepA: Benzyl 6-Diazopenicillanate

Benzyl 6-aminopenicillanate p-toluene sulfonic acid salt (0.5 g.) isadded to a mixture of methylene chloride (50 ml.), ice (50 cc.) andsodium nitrite (1.5 g.) and the mixture is thoroughly mixed. To theresulting mixture is added a total of 0.2 g. of p-toluenesulfonic acidin three equal amounts at intervals of 5 minutes, and the cold mixture(10° C.) is again mixed by shaking for 20 minutes. The yellow methylenechloride solution of benzyl 6-diazopenicillanate is then separated,dried over sodium sulfate at 0°-10° C., filtered and the dried solutionis evaporated at room temperature to about 5 ml.

Step B: Benzyl 6β-azido-6-bromopenicillanate

To a solution of benzyl 6-diazopenicillanate (2.0 g.) in methylenechloride (20 ml.) is added nitromethane (20 ml.) followed bytriethylammonium azide solution (20 ml.). The resulting reaction mixtureis cooled to 5° C., and to this cooled solution is added 20 ml. ofbromine azide solution over a period of 15 seconds. To the resultingcooled reaction mixture is added 50 ml. of tenth normal sodiumthiosulfate solution with vigorous agitation. After stirring for 2additional minutes, the solution gives a negative test with starchiodide paper. Sodium bicarbonate is then added to the solution, and themixture is stirred until CO₂ evolution ceases. The organic phase isseparated, and the aqueous phase is extracted with 20 ml. of methylenechloride. The combined organic phase is washed with saturated sodiumbicarbonate solution until no more evolution of CO₂ occurs. The organicphase is then dried over magnesium sulfate and evaporated to dryness togive 1.3 g. of crude benzyl 6-azido-6-bromopenicillanate.

The crude product is purified by absorbing it on 2.5 g. of silica gel,placing the absorbate on top of a column of 50 g. of silica gel in amixture of equal parts of hexane and benzene, developing the column withthe same solvent, collecting 200 ml. fractions of eluate, and recoveringa solution of benzyl 6β-azido-6-bromopenicillanate (0.550 g.) fromfractions 5-10. This product has a R_(f) of 0.60 (CHCl₃).

IR: 4.69μ (azido), 5.53μ (β-lactam structure) and at 5.71μ (ester)

NMR: 2.62 tau (s), (phenyl); 4.7 tau (s), (5H); 4.79 tau (s), (CH₂ ·C₆H₅); 5.47 tau (s), (3H); 8.41 tau (s); 8.63 tau (s), (gem CH₃), [(s)denotes singlet]

The triethylammonium azide solution is prepared by dissolving sodiumazide (3.0 g.) in water (10 ml.) cooling this solution to 0°-10° C.,adding methylene chloride (20 ml.) and then concentrated sulfuric acid(3.0 ml.) dropwise with rapid stirring, separating the organic phase,extracting the aqueous phase with methylene chloride (5.0 ml.), dryingthe combined aqueous phases over calcium chloride and addingtriethylamine to the dried solution until the pH is 7.0.

The bromine azide solution is prepared by cooling a mixture of sodiumazide (5.3 g.) and methylene chloride (16.0 ml.) to 5° C., addingbromine (1.28 g.) to the cooled mixture followed by concentratedhydrochloric acid (4.0 ml.) and allowing the stoppered mixture to stirat 0°-10° C. for three hours. The organic phase is separated from thepaste-like inorganic phase. The inorganic phase is washed with methylenechloride (4.0 ml.) and the organic phases are combined to give 20 ml. ofsolution.

Step C: Benzyl 6β-azido-6-methoxypenicillanate

To a solution of 0.55 g. of benzyl 6β-azido-6bromopenicillanate in 50ml. of methanol is added 0.334 g. of silver tetrafluoroborate, and thestoppered mixture is allowed to stir at room temperature for 21/2 hours.The methanol is then removed under reduced pressure, and the residue istaken up on 30 ml. of methylene chloride, filtered through diatomaceousearth and washed with a small quantity of methylene chloride. Thefiltrate and washing are washed once with a 5% solution of sodiumbicarbonate and then brine, dried and evaporated to give 0.464 g. ofcrude benzyl 6-azido-6-methoxypenicillanate. This product is purified bychromatography on 15 g. of silica gel, and the column is developed with70% hexane/benzene. The eluate is collected in 50 ml. fractions andfractions 12-26 evaporated to obtain benzyl 6,6-dibromopenicillanate.The column is then eluted with 70% benzene in hexane and fractions 28-39evaporated to yield 0.325 g. of desired product, benzyl6β-azido-6-methoxypenicillanate. This product has a R_(f) of 0.435(CHCl₃); IR, 4.70μ (azido), 5.58μ (β-lactam), and 5.71μ (ester); and NMRin CDCl₃ 2.62 tau (s), (phenyl); 4.60 tau (s), (5H); 4.78 tau (s), (CH₂C₆ H₅); 5.47 tau (s), (3H); 6.35 tau (s), (OCH₃); and 8.4 tau (s) and8.58 tau (s), (gem CH₃).

Step D: Benzyl 6β-acetamido-6-methoxypenicillanate

To a solution of 0.065 g. of benzyl 6-azido-6-methoxypenicillanate in 20ml. of acetic anhydride is added 0.065 g. of platinum oxide, and themixture is hydrogenated at atmospheric pressure for 18 hours. Theresulting solution is concentrated under reduced pressure at atemperature below 40° C. to remove the acetic anhydride. The resultingresidue is taken up in a mixture of equal volumes of methylene chlorideand ethyl ether and filtered through diatomaceous earth to remove thecatalyst. The filtrate and washings are evaporated under reducedpressure to afford 0.066 g. of benzyl6β-acetamido-6-methoxypenicillanate. The crude product is purified bythin layer chromatography to yield 0.03 g. of pure product. R_(f) of0.52 (2% CH₃ OH/CHCl₃);

IR: 5.59 μ (β-lactam) and 5.71μ (ester).

NMR: 2.63 tau (s), (phenyl); 4.4 tau (s), (5H); 4.80 tau (s), (CH₂ C₆H₅); 5.52 tau (s), (3H); 6.53 tau (s), (OCH₃); 7.9 tau (s), ##STR10##8.45 tau (s) and 8.60 tau (s), (gem CH₃).

Step E: 6β-Acetamido-6-methoxypenicillanic Acid and Sodium Salt

A solution of benzyl 6β-acetamido-6-methoxypenicillanate (0.03 g.) in amixture of dioxane (2 ml.), methanol (4 ml.) and water (2 ml.) ishydrogenated using 10% palladium on charcoal (0.03 g.) at 40 p.s.i. forone hour. The catalyst is removed and the solvents are removed in vacuoat room temperature. To the residue of6β-acetamido-6-methoxypenicillanic acid is added a solution of sodiumbicarbonate (0.03 g.) in water (10 ml.). The bicarbonate solution iswashed with methylene chloride and the aqueous phase freeze dried toafford sodium 6β-acetamido-6-methoxypenicillanate. This compound shows azone of inhibition against B-Subtilis.

EXAMPLE 2 Benzyl 6β-acetamido-6-methoxypenicillanate Step A: Benzyl6-methoxy-6-aminopenicillanate

To a solution of benzyl 6-methoxypenicillanate (0.045 g.) in ethylacetate (8.0 ml.) is added 0.045 g. of 10% palladium-on-charcoal. Themixture is reduced under hydrogen at atmospheric pressure for 20 hours.The catalyst is removed by filtration and the filtrate evaporated todryness to afford crude benzyl-6-methoxy-6-aminopenicillanate. Thinlayer chromatography shows one major spot, R_(f) 0.52 (2% methanol,chloroform, silica gel plates). The spot gives a positive ninhydrintest. When this product is further purified by thin layerchromatography, the product obtained exhibits, in its infrared spectrum,a β-lactam and an ester carbonyl at 5.59 and 5.71μ, respectively, andN-H at 2.90μ. No azide function is observed.

Step B: Benzyl 6β-acetamido-6-methoxypenicillanate

Benzyl 6-methoxy-6-aminopenicillanate is treated with acetic anhydride(2.0 ml.) for one hour at room temperature. The acetic anhydride is thenevaporated under reduced pressure and the residue purified bypreparative thin layer chromatography to afford product having β-lactam,ester and amide carbonyl in the infrared and a R_(f) on thin layerchromatography essentially identical to that of benzyl6β-acetamido-6-penicillanate obtained in Example 1, Step D.

EXAMPLE 3 6β-Phenylacetamido-6-methoxypenicillanic Acid Sodium Salt StepA: Benzyl 6β-phenylacetamido-6-methoxypenicillanate

To a solution of benzyl 6-β-azido-6-methoxypenicillanate (0.5 g.),phenylacetic anhydride (2.5 g.) and dioxane (20 ml.) is added platinumoxide (0.25 g.) and the resulting mixture is hydrogenated at atmosphericpressure for 20 hours. The dioxane is removed under reduced pressure,and the residue is chromatographed on 30 g. of silica gel. The column isdeveloped with benzene to remove unreacted phenylacetic anhydride andany unreacted azide. The column is eluted with chloroform, and five 50ml. fractions of eluate are evaporated to afford the crude product mixedwith phenylacetic acid. The crude product is dissolved in 30 ml. ofmethylene chloride, washed once with 5% solution of sodium bicarbonate,dried over magnesium sulfate and evaporated to afford 0.175 g. of thebenzyl ester of 6-methoxy benzylpenicillin. This product ischromatographed on silica gel using a methylene chloride-ethyl acetategradient to obtain 0.06 g. of pure benzyl6β-phenylacetamido-6-methoxypenicillanate. This product has a R_(f) of0.434 (2% CH₃ OH/CHCl₃); IR, 5.59μ (β-lactam), 5.71μ (ester), 5.95μ(amide I) and 6.58μ (amide II); NMR, 2.65 tau (s), (C₆ H.sub. 5); 4.41tau (s), (5-H); 4.81 tau (s), (OCH₂ C₆ H₅); 5.59 tau (s), (3H); 6.35 tau(s), (COCH₂ C₆ H₅); 6.60 tau (s), (O C H₃); and 8.64 tau (s), (gem CH₃).

Step B: 6β-Phenylacetamido-6-methoxypenicillanic Acid Sodium Salt

To a solution of benzyl 6β-phenylacetamido-6-methoxypenicillanate (0.317g.) in a mixture of dioxane (9.0 ml.), methanol (5.0 ml.) and water (10ml.) is added 0.317 g. of 10% palladium-on-carbon and sodium bicarbonate(0.063 g.). The mixture is hydrogenated at 40 p.s.i. for two hours. Thecatalyst is filtered off, the pH of the filtrate adjusted to 7.3 andmost of the dioxane and methanol removed under reduced pressure at atemperature below room temperature. The resulting aqueous solution iswashed twice with methylene chloride and the aqueous phase is freezedried. The freeze dried material is stirred with anhydrous methanol (20ml.) and the insoluble inorganic material filtered off. The filtrate isevaporated below room temperature to afford 0.208 g. of sodium6β-phenylacetamido-6-methoxypenicillanate.

IR: 5.65μ (β-lactam), 5.95β (amide I) and 6.19μ (COO-);

NMR: 2.58 tau (s), (C₆ H₅); 4.45 tau (s), (5H); 5.72 tau (s), (3H); 6.27tau (s), (COCH₂ C₆ H₅); 6.48 tau (s), (OCH₃); and 8.55 tau (s) and 8.58tau (s), (gem CH₃).

EXAMPLE 4 6β-Phenoxyacetamido-6-methoxypenicillanic Acid Sodium SaltStep A: Benzyl 6β-phenoxyacetamido-6-methoxypenicillanate

To a solution of benzyl 6β-azido-6-methoxypenicillanate (0.075 g.) indioxane (4.0 ml.) containing phenoxyacetic anhydride (0.403 g.) is addedplatinum oxide (0.075 g.) and the mixture is hydrogenated for 18 hourswith agitation under 34 p.s.i. of hydrogen. The resulting mixture isconcentrated in vacuo at room temperature, and the residue is absorbedon a column containing 20 g. of silica gel with benzene. The product iseluted from the absorbate with chloroform along with phenoxyacetic acid.The combined fractions consisting of 0.377 g. are dissolved inchloroform and washed three times with a 5% solution of sodiumbicarbonate. The chloroform solution is then concentrated, and theresidue is rechromatographed on 5 g. of silica gel which is eluted with2-3% ethyl acetate/methylene chloride, and the eluate is evaporated toafford benzyl 6β-phenoxyacetamido-6-methoxypenicillanate.

IR: 3.00μ, 5.63μ, 5.74μ, 5.91μ

Step B: 6β-Phenoxyacetamido-6-methoxypenicillanic Acid Sodium Salt

A solution of benzyl 6β-phenoxyacetamido-6-methoxypenicillanate (0.028g.) in 8 ml. of solvent (dioxane: methanol:water - 1:2:1) containing0.028 g. of 10% platinum-on-charcoal is hydrogenated at 40 p.s.i. forone hour. The catalyst is removed by filtration, and the organicsolvents are removed by evaporation in vacuo at room temperature toafford 6-methoxy phenoxypenicillanic acid to which is added a solutionof sodium bicarbonate (0.06 g.) in water (10.0 ml.). The resultingaqueous solution is then extracted with a small quantity of methylenechloride and lyophilized to afford sodium6β-phenoxyacetamido-6-methoxypenicillanate.

IR: 5.66μ, 5.91μ, 6.0μ

EXAMPLE 5 Sodium 6β-methoxy-6-phenylacetamidopenicillanate Step A:Benzyl 6β-bromo-6-methoxypenicillanate

To a solution of benzyl 6-diazopenicillanate (2.0 g.) in methylenechloride (20 ml.) is added a cold solution of N-bromoacetamide (56 g.)in methanol (20 ml.). The mixture is kept at ambient temperature for 30minutes and then the solvents rapidly removed under reduced pressure.The gummy residue is dissolved in methylene chloride and washed with anaqueous sodium bicarbonate solution. The methylene chloride solution isdried over magnesium sulfate, filtered and evaporated. The residue ischromatographed on a column of silica gel (60 g.) which is eluted with a1:1 mixture of a hexane and methylene chloride solution. A centerfraction of 860 mg. of benzyl 6β-bromo-6-methoxypenicillanate isobtained which solidifies on standing. A sample, recrystallized frometherpetroleum ether melts at 90°-91° C. NMR in CDCl₃ 4.55 tau (s),(5H); 5.48 tau (s), (3H); 6.36 tau (s), (OCH₃); 8.4 tau (s), 8.62 tau(s), (gem CH₃). IR is 5.62μ (β-lactam) and 5.78μ (ester) (nujol mull).

Elemental analysis

Calc.: C, 48.01; H, 4.53; N, 3.50; Br, 19.96; Found: C, 47.53; H, 4.30;N, 3.60; Br, 20.65.

Step B: Benzyl 6-α-azido-6-methoxypenicillanate

A solution of benzyl 6β-bromo-6-methoxypenicillanate (640 mg.) and 435mg. of lithium azide in 5 ml. of dimethylformamide is kept at 30°-35° C.for 6 hours. The dimethylformamide is evaporated under high vacuum andthe residue taken up in a mixture of 50 ml. of carbon tetrachloride and75 ml. of water. The aqueous layer is descarded, and the organic layeris washed twice more with water to remove residual dimethylformamide.The carbon tetrachloride phase is dried and evaporated and the residualoil chromatographed on a column of 20 g. silica gel. Elution with 50%hexane-methylene chloride gives 0.56 g. of benzyl6-α-azido-6-methoxypenicillanate. NMR in CDCl₃ is 4.73 tau (s), (5H);5.5 tau (s), (3H); 6.43 tau (s), (OCH₃); 8.41 tau (s) and 8.62 tau (s),(gem CH₃). IR is 4.74μ (azide), 5.60μ (β-lactam) and 5.76μ (ester)(film).

Elemental analysis for C

Calc.: C, 53.03; H, 5.0; N, 15.46; Found: C, 52.92; H, 5.13; N, 15.69.

Step C: Benzyl 6β-methoxy-6-phenylacetamidopenicillanate

A mixture of benzyl 6-α-azido-6-methoxypenicillanate (150 mg.),diisopropyl ethylamine (0.1 ml.) and 75 mg. of 10% palladium-on-charcoalcatalyst in dry ethylacetate (1.5 ml.) is hydrogenated at atmosphericpressure and room temperature for 3 hours. To the resulting solution ofbenzyl 6-α-amino-6-methoxypenicillanate is added a solution ofphenylacetic anhydride (200 mg.) in methylene chloride (5 ml.). Themixture is stirred at room temperature for 20 minutes, then the catalystis removed by filtration and the solvents evaporated. The residue ischromatographed on 20 g. of silica gel. Methylene chloride is passedthrough the column until the eluate is free of phenylacetic acid, andthe product is eluted with 2% ethylacetate in methylene chloride. 75 Mg.of benzyl 6β-methoxy-6-phenylacetamidopenicillanate is obtained.

NMR: 2.63 tau (s) and 2.68 tau (s), (phenyl); 4.3 tau (s), (5H); 4.8 tau(s), (OCH₂ C₆ H₅); 5.53 tau (s), (3H); 6.35 tau (s); ##STR11## 6.51 tau(s), (OCH₃); 8.43 tau (s) and 8.61 tau (s), (gem CH₃). IR is 5.65μ(β-lactam), 5.75μ (ester) and broad band 5.92-6.02μ (amide) (film).

Step D: Sodium 6β-methoxy-6-phenylacetamidopenicillanate

A solution of 75 mg. of benzyl 6β-methoxy-6-phenylacetamidopenicillanateand 24 mg. of sodium bicarbonate in 2.2 ml. of dioxane, 2.5 ml. waterand 1.2 ml. of methanol is hydrogenated in the presence of 75 mg. of 10%palladium-on-charcoal catalyst at room temperature at 30 p.s.i.g. fortwo hours. The catalyst is filtered off and the filtrate evaporatedunder vacuum to dryness. The residue is taken up in water, extractedonce with methylene chloride and the aqueous layer freeze-dried. 51 mg.of solid is obtained containing sodium6β-methoxy-6-phenylacetamidopenicillanate.

IR: 5.67μ (lactam)

NMR: (Solvent - D₂ O) 2.67 tau (s), (phenyl); 4.53 tau (s), (5H); 5.72tau (s), (3H); 6.38 tau (s), (φ-CH₂); 6.58 tau (s), (OCH₃); 8.45 tau (s)and 8.49 tau (s), (gem CH₃).

EXAMPLE 6 6-α-Azido-6-bromopenicillanic Acid Step A:N,O-Bis-trimethylsilyl 6-aminopenicillanate

A suspension of 6-aminopenicillanic acid (0.433 g., 0.002 mole) inchloroform (8 ml.) and hexamethyldisilazane (2 ml.) is heated at refluxfor 24 hours protected from moisture. The chloroform and the excesshexamethyldisilazane are removed at reduced pressure leaving anamber-colored, viscous oily residue (665 mg.) of N,O-bis-trimethylsilyl6-aminopenicillanate. The IR and NMR spectra are in agreement with thestructure.

Step B: Trimethylsilyl 6-diazopenicillanate

A solution of N,O-bis-trimethylsilyl 6-aminopenicillanate (0.53 g.) inchloroform (5 ml.) and trifluoroacetic acid (8 drops) is stirred in anice bath and isoamyl nitrite (0.3 ml.) added. After one hour, aninfrared absorption spectrum is taken and a strong band at 4.78μ(representing the presence of the diazo group) is present. The solutionis used directly in the next step.

Step C: 6-α-Azido-6-bromopenicillanic Acid

The chloroform solution of trimethylsilyl 6-diazopenicillanate isdiluted with cold nitromethane (8 ml.). Methylene chloride solutions (5ml.) of triethylammonium azide and 5 ml. bromine azide (both in excessof the required amounts) are added in succession. Nitrogen gas isevolved. After about 5 minutes, 10 ml. of 0.1N sodium thiosulfatesolution is added. A few drops of 3N hydrochloric acid are also added toadjust the solution to pH 3, and the layers are separated. The aqueousphase is extracted twice more with chloroform. The combined chloroformextracts are washed once with water, dried, filtered and concentratedleaving 0.104 g. of 6-α-azido-6-bromopenicillanic acid. The infraredabsorption spectrum (CHCl₃ solution) shows the presence of significantbands at 4.7μ (azido), at 5.6μ (β-lactam structure), and at 5.77μ(carboxylic acid).

EXAMPLE 7 Benzyl 6β-azido-6-methoxypenicillanate Step A: Epimerizationof benzyl 6β-bromo-6-methoxy-penicillanate

A solution of benzyl 6β-bromo-6-methoxypenicillanate (200 mg.) andlithium bromide (0.2 g.) in dimethylformamide (1.5 ml.) is stirred atroom temperature overnight. The DMF is removed in vacuo, and the residueis taken up in chloroform and washed with water. The chloroform solutionis evaporated leaving an equilibrium mixture containing 23% of theβ-bromo isomer and 77% of the α-bromo isomer as determined by NMRanalysis. Chromatography on silica gel with gradient elution byincreasing concentration of methylene chloride in hexane yields 90 mg.of crystalline benzyl 6-α-bromo-6-methoxypenicillanate, m.p. 41°-43° C.NMR is 4.26 tau (s), (5H); 5.48 tau (s), (3H); 6.38 tau (s), (OCH₃);8.47 tau (s) and 8.60 tau (s), (gem CH₃). IR is 5.59μ (β-lactam) and5.75μ (ester) (nujol mull).

Step B: Benzyl 6β-azido-6-methoxypenicillanate

A solution of 90 mg. of benzyl 6-α-bromo-6-methoxypenicillanate (m.p.41°-43° C.) in 1.5 ml. of N lithium azide in dimethylformamide is keptat room temperature for 3 hours. The dimethylformamide is pumped off invacuo and the residue taken up in carbon tetrachloride and water. Themixture is centrifuged and the upper aqueous layer removed. The organiclayer is washed three times with water, then dried and evaporated,giving 50 mg. of the benzyl ester 6β-azido-6-methoxypenicillin identicalwith the compound obtained in Example 1, Step C.

EXAMPLE 8 6β-(D-α-aminophenylacetamido)-6-methoxypenicillanic Acid StepA: D(-)-α-azidophenylacetyl Chloride

D(-)-α-azidophenylacetic acid (2.29 g.) is dissolved in benzene and thesolution cooled to 10° C. in an ice bath. Thionyl chloride (11.5 ml.) isadded dropwise. The reaction mixture is warmed to room temperature andthen refluxed for 1/2 hour. The reaction mixture is cooled to roomtemperature and the solvent is evaporated on the vacuum pump to afford2.5 g. of D(-)-α-azidophenylacetyl chloride as a yellow oil.

IR: λ_(max).^(cm).spsp.-1 (CH₂ Cl₂) 2120 (azido), 1790 (C=O).

Step B: 6β-(D-α-aminophenylacetamido)-6-methoxypenicillanic Acid

Benzyl 6β-azido-6-methoxypenicillanate (1.0 g.) is dissolved in dryethyl acetate (80 ml.), N,N-diisopropylethylamine (4 ml.) and 10%palladium on carbon (1.0 g.) is added. The reaction mixture is stirredovernight under hydrogen at atmospheric pressure. The catalyst isfiltered off and the solvent evaporated. The residue is dissolved inmethylene chloride (100 ml.) and placed in an ice bath at 10° C.Pyridine (20 ml.) is added and then D(-)-α-azidophenylacetyl chloride(1.45 g.) added in one portion. After stirring 45 minutes the mixture ispoured onto ice containing sodium bicarbonate (1.0 g.). The two layersare separated and the aqueous layer washed successively with 3 portionsof methylene chloride. The combined methylene chloride layers are washedwith water, dried over magnesium sulfate, filtered and evaporated toafford a dark red oil. This reaction is repeated two more times and theproducts combined and placed on a column of silica gel (60 gm.) inbenzene. Elution is with benzene with 200 ml. fractions being taken.Fractions 11-23 contain 0.981 of product which is dissolved in methanol(100 ml.) and water (100 ml.) added 1.96 gm. of 10% palladium on carbonis added and the mixture placed on a Parr Shaker for two hours. Thecatalyst is removed by filtration. The organic solvents are removed bydistillation. The remaining aqueous solution is washed with two portionsof methylene chloride, the combined methylene chloride solutions arewashed once with water. The combined aqueous layers are freeze dried toafford 0.5 gm. of 6β-(D-α-aminophenylacetamido)-6-methoxypenicillanicacid. TLC: R_(f) 0.65 in butanol, acetic acid and water (3:1:1) IR:λ_(max).^(cm).spsp.-1 nujol 1765 (β-lactam), 1700 (amide), 1600 (COO-)

NMR: (CD₃ OD) 7.4 (m, phenyl), 5.55 (s, 6H), 4.1 (s, 3H), 3.5 (s,-OCH₃), 1.39 and 1.12, (s, 2 CH₃ 's).

EXAMPLE 9 Sodium 6-methoxy-6-phenylacetamidopenicillanate

Benzyl 6-bromo-6-phenylacetamidopenicillanate (1.06 g.) is treated with0.28 ml. of triethylamine in 10 ml. of methylene chloride to form benzyl6-phenylacetiminopenicillanate which is reacted with methanol to affordbenzyl 6-methoxy-6-phenylacetamidopenicillanate. The ester ishydrogenated with palladium on charcoal catalyst in aqueous methanol inthe presence of one equivalent of sodium bicarbonate to afford sodium6-methoxy-6-phenylacetamidopenicillanate.

EXAMPLE 10 Sodium 6-Thienylacetamido-6-methylthiopenicillanate Step A:Benzyl 6-bromo-6-methylthio penicillanate

Ten millimoles of benzyl diazo penicillanate dissolved in methylenechloride (100 ml.) is cooled to -40° C. under N₂. To this, 12 millimolesof methylsulfenyl bromide in methylene chloride (100 ml.) is addeddropwise with vigorous stirring. Nitrogen evolution is immediate. Afteraddition of the reagent (15 minutes) at -40° C. the mixture is allowedto warm gradually to -5° C. Saturated sodium bicarbonate solution isadded and the organic layer separated and washed with water. Afterdrying over sodium sulfate the solvent is removed at room temperature invacuo to afford benzyl 6-bromo-6-methylthio penicillanate. The crudeproduct is evaluated by ir (loss of diazo 2100 cm⁻¹, presence ofβ-lactam 1790 cm⁻¹) and positive Beilstein test for halogen. The crudeproduct may be further purified by preparative tlc or columnchromatography.

Step B: Preparation of Benzyl 6-azido-6-methylthio penicillanate

Ten millimoles of benzyl 6-bromo-6-methylthio penicillanate are heatedfor 4 minutes at 68° C. in 60 ml. DMF which contains 10 millimoleslithium azide. The solution is diluted with 300 ml. water and extracted2 × 50 ml. chloroform. The chloroform layer is washed 3 × 100 ml. waterand dried over anhydrous sodium sulfate. The solution is filtered andthe solvent removed to afford preparation of benzyl 6-azido-6-methylthiopenicillanate.

Step C: Preparation of benzyl 6-thienylacetamido-6-methylthiopenicillanate

Ten millimoles of benzyl 6-azido-6-methylthio penicillanate aredissolved in 50 ml. of ethyl acetate and 10 millimoles of thienylaceticanhydride, 0.1 ml. pyridine and 800 mg. 10% palladium on carbon areadded. The mixture is hydrogenated at room temperature for one hour. Thecatalyst is removed by filtration and the residue evaporated to affordbenzyl 6-thienylacetamido-6-methylthio penicillanate.

Step D: Sodium 6-thienylacetamido-6-methylthio penicillanate

By following the procedure of Example 1, Step E, and by substitutingbenzyl 6-thienylacetamido-6-methylthio penicillanate for the benzyl6β-acetamido-6-methoxy penicillanate described therein, there isobtained sodium 6-thienylacetamido-6-methylthio penicillanate.

Step E: Sodium 6-thienylacetamido-6-ethylthio penicillanate

By following the procedure of Step A, except that ethyl sulfenylbromideis used as reagent, the intermediate compound benzyl-6-bromo-6-ethylthio penicillanate is prepared. This is used, followingthe Steps B-D to prepare sodium 6-thienylacetamido-6-ethylthiopenicillanate.

EXAMPLE 11 6-Methoxy-6-Phenylmalonacetamidopenicillanic Acid andDisodium Salt Step A: Benzyl Phenylmalonic acid

An ether solution of phenyldiazomethane is prepared by adding 87 g.(0.31 mole) of N-nitroso-N-benzyl-p-toluenesulfonamide portionwise overone hour to a well stirred mixture of 17 g. of sodium methoxide (0.315mole) in 60 ml. of methanol and 360 ml. of ether. The thick pink slurryis refluxed for 20 minutes, then cooled and 300 ml. of ice water isadded. The organic phase is washed with 3 × 200 ml. of water, dried oversodium sulfate and filtered to yield 360 ml. of a dark red etheralsolution of phenyldiazomethane. To a solution of phenylmalonic acid(18.2 g) in 200 ml. of ether is added 350 ml. of the phenyldiazomethaneether solution over ten minutes, while maintaining the temperature at0°-5° C (nitrogen evolution). The yellow solution is stirred for tenminutes, 500 ml. of water is added and the pH of the mixture adjusted topH=10 with 2N potassium hydroxide. The layers are separated, the waterlayer is extracted with 500 ml. of ethyl acetate, and the combinedorganic phases extracted with 250 ml. of water. Ethyl acetate, 500 ml.,is added to the combined aqueous extracts and adjusted to pH=2 with 2Nhydrochloric acid with stirring and ice cooling. The aqueous phase isextracted with 200 ml. of ethyl acetate, the combined organic phases aredried over sodium sulfate and concentrated to dryness to yield 25 g. ofyellow oil. A TLC (silica gel/10%MeOH in CH₂ Cl₂) showed two spots, Rf0.1 and Rf 0.5. Chromatography on 250 g. of silica gel elution with 2%methanol in methylene chloride yielded 14 g. (52%) of pure benzylphenylmalonic acid, m.p. 45°-50° C, single spot by TLC, Rf 0.5. The IRin morpholine is consistent with the assigned structure, an ester bandat 5.8μ and a broad carboxylate band at 6.3μ.

Step B: Benzyl Phenylmalonic Acid Chloride

Eight grams of benzyl phenylmalonic acid is dissolved in 8 ml. of oxalylchloride and let stand at room temperature for one hour. The excessoxalyl chloride is removed under vacuum (bath temp. 25° C) and theresidue flushed with 10 ml. of dry benzene to yield about 8 g. of benzylphenylmalonic acid chloride as a pale yellow oil, which is usedimmediately in the next step. An N M R in CDCl₃ showed a shift in theφCH proton from 4.8τ to 5.0τ. The IR is consistent with the assignedstructure with an acid chloride band at 5.6μ and a benzyl ester band at5.7μ.

Step C: Benzyl 6-Amino-6-methoxypenicillinate

Eight grams of benzyl 6-azido-6-methoxypenicillinate, dissolved in amixture of 200 ml. of ethyl acetate and 12 ml. ofN,N-diisopropylethylamine is hydrogenated over 16 g. of 10%palladium-on-carbon catalyst at room temperature and 40 psi. for 50minutes. The catalyst is filtered off and the filtrate concentratedunder vacuum at room temperature and pumped to yield 8.0 g. of a tanoil. The IR (in dichloromethane) showed a strong lactam band at 5.6μ, anester band of equal intensity at 5.85μ, while the azide band of thestarting material is totally absent. A TLC (silica gel/2% MeOH in CH₂Cl₂) showed several spots with the desired amine, Rf. 0.54, giving apink color with ninhydrin spray. The oil is used without furtherpurification in the next step.

Step D: Dibenzyl 6-Methoxy-6-phenylmalonacetamidopenicillinate

Eight grams of benzyl 6-amino-6-methoxypenicillinate is dissolved in 160ml. of dichloromethane and chilled to -5° C. Pyridine (4.0 g) is addedfollowed by the dropwise addition of 8 g. of benzyl phenylmalonic acidchloride in 160 ml. of dichloromethane over a 5 minute period. The pH ofthe pale yellow solution is neutral. After stirring for 30 minutes atroom temperature, the mixture is washed with 3 × 200 ml. of water, theorganic layer is dried over sodium sulfate and concentrated to drynessto yield 15 g. of a yellow oil. A TLC (silica gel/2% MeOH in CH₂ Cl₂)shows several spots with major components at Rf's 0.5, 0.6, and 0.7,with the desired amide at Rf 0.6 prevailing. Chromatography on 300 g. ofsilica gel (Baker), eluted with 200 ml. portions of dichloromethane withfractions 11-24 containing 4.0 g. of purified product, showing the majorspot at Rf 0.6 and some minor impurities. A second similarchromatography on 100 g. of silica gel gave 2.0 g. (15% over two steps)of pure dibenzyl 6-methoxy-6-phenylmalonacetamidopenicillinate, singlespot, Rf 0.6. The IR is consistent with the assigned structure, with alactam band at 5.65μ, an ester band of equal intensity at 5.75μ and anamide band of lesser intensity at 5.9μ.

Step E: 6-Methoxy-6-phenymalonacetamidopenicillanic Acid Disodium Salt

A solution of 2.0 g. of dibenzyl6-methoxy-6-phenylmalonacetamidopenicillinate in 200 ml. of a mixture ofdioxane, methanol and water (1:2:1) is hydrogenated over 4 g. of 10%palladium-on-carbon at room temperature, at 40 psi. for one hour. Afterfiltration and concentration to dryness at room temperature, the6-methoxy-6-phenylmalonacetamido penicillanic acid is converted to itsdisodium salt by dissolving in 25 ml. of water containing 0.5 g. ofsodium bicarbonate. The aqueous solution is extracted with 3 × 25 ml. ofdichloromethane, then freeze-dried to yield 1.2 g. of pure6-methoxy-6-phenylmalonacetamidopenicillanic acid disodium salt (74%) asa pale yellow powder. The IR is consistent with the proposed structure,with α β-lactam band at 5.65μ, an amide band at 5.95μ and a broadcarboxylate band at 6.3μ. A TLC (silica gel/n-BuOH-H₂ O-HOAc, 4:1:1)shows essentially a single spot. A Karl Fisher titration gave 2.5% H₂ O(after correction due to NaHCO₃ →H₂ O + CO₂ + Na₂ CO₃). Estimating 4% ofsodium bicarbonate and 2% of water to be present, gives the correctedelemental analysis:

Calcd. (corr): C, 45.58; H, 4.02; N, 5.82; S, 6.65; Na, 10.65, Found: C,45.56; H, 4.24; N, 5.59; S, 6.60; Na, 11.10.

Example 12 Benzyl 6-Diazopenicillanate-S-oxide Step A Benzyl6-Aminopenicillanate-S-oxide, p-toluenesulfonic Acid Salt

Benzyl 6-aminopenicillanate p-toluene sulfonic acid salt (.5 g.) istaken up in 25 ml. of methylene chloride, 10 ml. of water and 0.081 g.of sodium bicarbonate is added. The mixture is shaken and the aqueousphase is discarded. The organic phase is dried over MgSO₄ and evaporatedto give 0.320 g. of benzyl 6-aminopenicillanate which is dissolved in 10ml. methylene chloride and treated with 0.180 g. of m-chloro per benzoicacid for 1 hour. The mixture is diluted with methylene chloride andwashed three times with 5% NaHCO₃, and once with water. The methylenechloride solution is dried, filtered and evaporated. The residue istaken up in acetone (10 ml.) cooled to -5° C. and 0.200 g. of p-toluenesulfonic acid is added. The mixture is allowed to stand at -5° C. for 1hour. The crystallized solid is filtered and washed with acetone at 0°C. to give benzyl 6-aminopenicillanate-S-oxide, p-toluenesulfonic acidsalt. m.p. 159°-161° C. I.R.: 5.57 (β lactam carbonyl), 5.72 μ (estercarbonyl)

Step B Benzyl 6-aminopenicillanate-S-oxide

Benzyl 6-aminopenicillanate-1-oxide, p-toluenesulfonic acid salt (0.164g.) is taken up in 10 ml. of methylene chloride nad 10 ml. of water.Sodium bicarbonate (0.028 g.) is added and the mixture is shaken and theorganic phase is separated, dried over MgSO₄ and evaporated to give0.102 g. of benzyl 6-aminopenicillanate-S-oxide. I.R.: 6.62 μ (βlactam), 5.72 μ (ester carbonyl).

NMR: 2.61δ, φ; 4.75δ (AB quartet), CH₂ --C₆ H₅ ; 5.07δ 5.3δ (5H 6H pairof doublets) 5.34δ, (3H); 7.75δ (NH₂); 8.35 8.91, (gem dimethyl).

Step C Benzyl 6-Diazopenicillanate-S-oxide

Benzyl 6-aminopenicillanate-1-oxide (0.32 g.) is dissolved in 25 ml. ofmethylene chloride, 10 g. of ice is added and 0.100 g. of sodiumnitrite. The mixture is shaken and then 0.400 of p-toluene sulfonic acidis added in 4 equal amounts over a period of 10 minutes with vigorousshaking. The aqeuous phase is then separated and the yellow organicphase is worked once with water dried over sodium sulfate, andevaporated to afford benzyl 6-diazopenicillanate-S-oxide.

The products of this invention may be used alone or in combination asthe active ingredient in any one of a variety of pharmaceuticalpreparations. These antibiotics and their corresponding salts may beemployed in capsule form or as tablets, powders or liquid solutions oras suspensions or elixirs. They may be administered orally,intravenously or intramuscularly. Suitable carriers which may be used inthe composition include, for example, mannitol, sucrose, glucose orsterile liquids such as water, saline, glycols and oils of petroleum,animal, vegetable or synthetic origin as, for example, peanut oil,mineral oil or sesame oil. Also, in addition to a carrier the instantcompositions may include other ingredients such as stabilizers, binders,antioxidants, preservatives, lubricators, suspending agents, viscosityagents or flavoring agents. In addition, there may also be included inthe composition other active ingredients to provide a broader spectrumof antibiotic activity.

The dosage to be administered depends to a large extent upon thecondition of the subject being treated and the weight of the host, theparenteral route being preferred for generalized infections and the oralroute for intestinal infections. In general, a daily dosage consists offrom about 15 to about 600 mg. of active ingredient per kg. of bodyweight of the subject in one or more applications per day.

One typical unit dosage form consists in mixing 120 mg. of the sodiumsalt of 6-methoxy-6-phenoxyacetamido penicillanic acid with 20 mg. oflactose and 5 mg. of magnesium stearate and placing the 145 mg. mixtureinto a No. 3 gelatin capsule. Similarly, by employing more of the activeingredient and less lactose, other dosage forms can be put up in No. 3gelatin capsules and should it be necessary to mix more than 145 mg. ofingredients together, larger capsules such as compressed tablets andpills can also be prepared. The following example is illustrative

Dry-Filled Capsule Containing 120 mg. of the Sodium Salt of6-methoxy-6-phenoxyacetamidopenicillanic Acid:

    ______________________________________                                                           Per Capsule                                                Sodium salt of 6-methoxy-6-                                                   phenoxyacetamidopenicillanic                                                  Acid                 120 mg.                                                  Lactose               20 mg.                                                  Magnesium Stearate    5 mg.                                                   Capsule Size No. 3   145 mg.                                                  ______________________________________                                    

The sodium salt of 6-methoxy-6-phenoxyacetamidopenicillanic acid isreduced to a No. 60 powder and then lactose and magnesium stearate arepassed through a No. 60 bolting cloth onto the powder and the combinedingredients admixed for 10 minutes and then filled into No. 3 drygelatin capsules.

What is claimed is:
 1. A compound having the formula: ##STR12## where nis the integer 0 or 1; R₁ is lower alkylthio; and R is selected from thegroup consisting of hydrogen, lower alkyl, trimethylsilyl, benzyl,methoxybenzyl, and trichloroethyl; and pharmaceutical acceptable saltsthereof.
 2. A compound in accordance with claim 1 wherein R₁ ismethylthio.
 3. A compound according to claim 1 where n is
 0. 4. Acompound according to claim 1 where n is 1.